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1、四川大学计算机学院、软件学院实验报告学号_ 姓名：_ 专业:课程名称编译原理课程设计实验课时4实验项目手工构造C-Minus语言的词法分析器实验时间实验目的、意义1. 熟悉C-Minus语言的词法特点，构造 C-Minus的DFA2. 设计数据类型、数据结构3. 通过完成词法分析程序，巩固词法分析知识语言特点正则表达式注释：/*注释*/关键字：if else int return void while专用符号：+-*/=!=；,()ID = lette r+NUM = digit+letter = a-z，A-Zdigit = 0-9DFAeqINLE1NNEQCOMMENIT石2other/
2、定义数据类型TokenType typedef enumENDFILE,ERROR,IF,ELSE,INT,RETURN,VOID,WHILE,ID,NUM,数据类型数据结构设计ASSIGN,EQ ,LT, LE,GT,GE,NEQ,PLUS,MINUS,TIMES,OVER ,L PAREN,RPARE N,L BRACKET,RBRACKET, LBRACE,RBRACE,COMMA,SEMI Toke nType;/定义状态类型typedef enum START, LBUFFER,RBUFFER,INCOMMENT,INNUM,INID,INEQ,INLE,INGE,INNEQ,DC
3、NE StateType;/结构定义static struct char *str;Toke nType tok; reservedWordsMAXRESERVED=if,IF,else,ELSE,i nt,INT,return,RETURN,void,VOID ,while,WHILE;DFA代码映射方法双层CASE实现代码映射，外层 CASE关注状态变换，内层 CASE关注输入字符。 外层CASE-共有12个状态：START,LBUFFER,RBUFFER,INCOMMENT,INNUM,INID,INEQ,INLE,INGE,INNEQ,DON ,default ;内层CASE判断get
4、NextChar()获取的下一个字符使当前状态转换为其他状态。关键代码分析Toke nType getToke n( void)int toke nStri ngln dex=0;Toke nType curre ntToke n;StateType state=START;int save; /是否保存到 tokenStringwhile(state!=DONE)int c=getNextChar();save=TRUE;switch(state)case START:if(isdigit(c)state=INNUM;else if(isalpha(c)state=INID;else if(
5、c= ) | (c=t) | (c=n) save=FALSE;else if(c=)state=INEQ;else if(c=)state=INGE;else if(c=!)state=INNEQ;else if(c=/)state=LBUFFER;elsestate=DONE;switch(c)case EOF:save=FALSE;curre ntToke n=ENDFILE; break;case +:curre ntToke n=PLUS; break;case -:curre ntToke n=MINUS; break;case *:curre ntToke n=TIMES; br
6、eak;case (:curre ntToke n=LPAREN; break;case ):curre ntToke n=RPAREN; break;case :curre ntToke n=LBRACKET; break;case :curre ntToke n=RBRACKET; break;case :curre ntToke n=LBRACE; break;case :curre ntToke n=RBRACE; break;case ;:curre ntToke n=SEMI; break;case ,:curre ntToke n=COMM A; break;default:cu
7、rre ntToke n=ERROR; break;break;case LBUFFER:if(c=*)toke nStri ngln dex=0;save=FALSE; state=INCOMMENT;else if(c=EOF)state=DONE; curre ntToke n=ENDFILE;elsecurre ntToke n=O VER; state=DONE;break;case INCOMMENT: save=FALSE;if(c=*)state=RBUFFER;else if(c=EOF)state=DONE;curre ntToke n=ENDFILE;break;case
8、 RBUFFER:save=FALSE;if(c=/)state=START;else if(c=*)else if(c=EOF)state=DONE;curre ntToke n=ENDFILE;elsestate=INCOMMENT; break;case INNUM:if(!isdigit(c)un getNextChar(); save=FALSE; state=DONE;curre ntToke n=NUM; break;case INID:if(!isalpha(c)un getNextChar(); save =FALSE; state=DONE;curre ntToke n=I
9、D; break;case INEQ:if(c=) state=DONE; curre ntToke n=EQ;elseun getNextChar(); save =FALSE;state=DONE;curre ntToke n=ASSIGN; break;case INLE:if(c=)state=DONE; curre ntToke n=LE;elseun getNextChar(); save =FALSE;state=DONE;curre ntToke n=LT;break;case INGE:if(c=)state=DONE;curre ntToke n=GE;elseun get
10、NextChar(); save =FALSE; state=DONE; curre ntToke n=GT;break;case INNEQ:if(c=)state=DONE;curre ntToke n=NEQ;elseun getNextChar();save =FALSE;state=DONE;curre ntToke n=ERROR;break;case DONE:break;default:fprin tf(list in g,Sca nner Bug:state=%dn,state);state=DONE;curren tToke n=ERROR;break;if(save) & (toke nStri ngI ndex-pQsdoi 曲口 dlUH勺ul VE9 匚 * a 1POH PE 如也&黑誰-w囲I resevued. wor-d： int1D,name =b2S f2?vesemed. woid.： int29lD,nane =c2哼V31ID,nane =a31! 311D,naneinpu31, name =h32=32D,am? =in put32,nan&in put3333f34Hnane=oiitiu.c3434ID,
